﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication8
{
    class Program
    {
        static void Main(string[] args)
        {
            string s;
            string str = "1, 3, -6, 7";
            for (int i = 2; i < str.Length-2; i++)
            {
                 s=str.Remove(i, 2);
            }
            Console.WriteLine(s);
        }
    }
}
